This invention relates to polyurethane spray systems having improved flame-retardant properties, particularly those based on storage-stable isocyanate-reactive compositions containing flame retardants. Spray systems based on polyurethanes are known. For example, U.S. Pat. Nos. 5,192,594, 5,233,009, and 5,275,888. However, polyurethane spray systems having improved flame and smoke performance would be desirable. One object of the present invention was to develop polyurethane spray systems having such improved performance.
Another object of the invention was improvement in shelf-life stability of the isocyanate-reactive compositions used to prepare polyurethane spray systems without sacrificing flame properties of the polyurethane product. Shelf-life stability, as measured by change in reactivity with the isocyanate component, is often adversely affected by the addition of flame retardants, especially those based on phosphorus, zinc, antimony, and aluminum. E.g., U.S. Pat. No. 5,302,303. It has now been found that the use of certain tertiary amines provides isocyanate-reactive compositions having improved storage stability without adversely affecting the improved flame properties of the polyurethane spray systems of the invention.